JP2016089689A - Egr device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EGR device which can prevent the adhesion and accumulation of deposits in an EGR cooler without largely increasing a pressure loss and making difficult to largely secure a recirculation amount of a reflux gas.SOLUTION: A shut valve 13 which blocks a flow of a reflux gas 4' between a takeout port 2a of the reflux gas 4' in an exhaust manifold 2 up to an EGR cooler 7 is constituted, in a swing type, of: a valve seat 14 which is formed so as to surround a flow passage of the reflux gas 4' in an EGR line 5 at an upstream side of the EGR cooler 7; an arm 15 which reciprocally and circularly moves between an approximate position and a separate position with respect to the valve seat 14 with the vicinity of the valve seat 14 as a fulcrum; and a valve body 16 which is attached to a tip of the arm 15, fit and pressure-adhered to the valve seat 14 in the approximate position with respect to the valve seat 14, and blocks the flow passage of the reflux gas 4'.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an EGR device for recirculating a part of exhaust gas from the exhaust side to the intake side as a recirculation gas.

  Conventionally, in an automobile engine or the like, a part of exhaust gas is extracted as a recirculation gas from the exhaust side and returned to the intake side, and the recirculation gas returned to the intake side suppresses combustion of fuel in the engine and burns. Some have a so-called EGR (Exhaust Gas Recirculation) device that reduces the generation of NOx by lowering the temperature and performs exhaust gas recirculation.

  At this time, if the recirculated gas that is recirculated to the engine is cooled in the middle, the temperature of the recirculated gas decreases and the volume of the recirculated gas decreases, thereby effectively reducing the combustion temperature without significantly reducing the output of the engine. Generation of NOx can be reduced. For this reason, a shell-and-tube type EGR cooler is generally provided in the middle of the system for recirculating the reflux gas.

  FIG. 3 shows an example of a conventional EGR device, in which 1 is an engine, 2 is an exhaust manifold for collecting exhaust gas 4 discharged from each cylinder 3 of the engine 1, and 5 is an outlet from the exhaust manifold 2. An EGR line 7 for recirculating a part of the exhaust gas 4 extracted through 2a as a recirculation gas 4 'to the intake pipe 6 is provided in the middle of the EGR line 5, and the recirculation gas 4' is used as cooling water. 2 shows an EGR cooler that is water-cooled by heat exchange.

  Here, immediately after the EGR cooler 7 in the EGR line 5, an EGR valve 8 for controlling the recirculation amount of the reflux gas 4 'is provided, and in particular, post injection for regenerating the particulate filter is performed. At the time of implementation or in an operation state in which the HC concentration in the exhaust manifold 2 is high, the valve is fully closed.

  That is, in a state where the HC concentration in the reflux gas 4 ′ is high, HC polymerization is likely to occur due to cooling by the EGR cooler 7. Therefore, in order to avoid this, the EGR valve 8 is fully closed to recirculate the reflux gas 4 ′. The circulation is stopped.

  As prior art document information related to such an EGR device, for example, there is the following Patent Document 1 by the same applicant as the present invention.

JP 2004-270462 A

  However, the recirculation amount of the recirculation gas 4 ′ tends to increase due to strict exhaust gas regulations in recent years, and an EGR device that employs a butterfly EGR valve 8 that can easily cope with an increase in the recirculation amount of the recirculation gas 4 ′ Although such a butterfly EGR valve 8 has become mainstream, since the airtightness at the time of closing is low, even if the EGR valve 8 is fully closed, the reflux gas 4 ′ enters and exits through a slight gap. Inevitably, the recirculation gas 4 'repeatedly moves back and forth in the EGR cooler 7 due to the intermittent action of the exhaust pulsation, so that it is continuously cooled, and is thus included in the recirculation gas 4'. The HC component is polymerized by HC polymerization and deposits (incomplete combustion products) are easily generated, and the deposits adhere to and accumulate on the heat exchange part in the EGR cooler 7. Or worse decreases the efficiency of heat exchange Te, there is a possibility that or choked passage through which the recirculating gas 4 '.

  Therefore, the inventor of the present application, as shown in FIG. 4, arranges a highly airtight poppet type shut valve 9 between the outlet 2a for the reflux gas 4 ′ and the EGR cooler 7 (see FIG. 3), and the post During injection or when the exhaust manifold 2 has a high HC concentration, both the EGR valve 8 (see FIG. 3) and the shut valve 9 are closed to make the leakage of the reflux gas 4 'zero, and HC polymerization of HC components However, in the poppet type shut valve 9, the valve body 11 wraps around the valve body 11 through a gap generated by the air cylinder 12 floating from the valve seat 10. Since the reflux gas 4 ′ is allowed to flow, a large increase in pressure loss is unavoidable, and it is difficult to ensure a large amount of recirculation of the reflux gas 4 ′.

  The present invention has been made in view of the above circumstances, and deposit deposition in an EGR cooler without greatly increasing pressure loss or making it difficult to ensure a large amount of recirculation of the reflux gas. An object of the present invention is to provide an EGR device that can prevent the above-described problem.

  The present invention is equipped with an EGR line that guides the recirculated gas extracted from the exhaust system path to the intake system path, an EGR cooler that is provided in the middle of the EGR line to cool the recirculated gas, and is provided on the outlet side of the EGR cooler. An EGR device comprising: an EGR valve that controls a recirculation amount of the recirculation gas; and a shut valve that blocks a flow of the recirculation gas from the recirculation gas outlet to the EGR cooler in the exhaust system passage. The valve seat formed to surround the flow path of the recirculation gas in the EGR line upstream from the EGR cooler, and the position close to the valve seat and the separated position with the valve seat as a fulcrum The shutter is constituted by an arm that moves in an arc and a valve body that is mounted on the tip of the arm and that is fitted to the valve seat at a position close to the valve seat to close the flow path of the reflux gas. It is characterized in that to constitute a valve swing.

  Thus, by adopting such a configuration, the shut valve is a swing type, so that the valve body can be largely separated from the valve seat and the flow path of the reflux gas can be opened to the maximum. Therefore, the pressure loss is greatly reduced and the recirculation of the recirculation gas is performed compared with the case where a poppet type shut valve is used. The amount can be easily increased.

  In addition, since the valve body is fitted and pressed against the valve seat formed inside the EGR line upstream from the EGR cooler so as to achieve a highly airtight blockage, the shut valve is closed when the EGR valve is fully closed. Thus, if the upstream side of the EGR cooler is also tightly closed, the reflux gas is prevented from entering and leaving the EGR cooler through a slight gap.

  As a result, the movement of the recirculation gas in the EGR cooler due to the intermittent action of the exhaust pulsation is not repeated, and the situation where the recirculation gas is continuously cooled in the EGR cooler is avoided. As a result, deposit deposition in the EGR cooler is prevented.

  In practicing the present invention, the angle range of the reciprocating arc motion of the arm is set to 90 ° so that the valve body can be retracted to a position where it does not interfere with the flow of the reflux gas flowing out from the flow passage surrounded by the valve seat. It is preferable to set it as described above. By doing so, interference between the valve body and the flow of the reflux gas is reliably avoided when the shut valve is fully opened, and the pressure loss is further reduced.

  Further, it is preferable that the reciprocating arc movement of the arm is performed by converting the reciprocating linear movement of the actuator via the lever. In this way, the pressing load of the valve body on the valve seat is controlled by the lever ratio. Thus, it is possible to make adjustments, and it is possible to set a proper pressing load and ensure high airtightness.

  According to the EGR device of the present invention described above, various excellent effects as described below can be obtained.

  (I) According to the invention described in claim 1 of the present invention, when the shut valve is fully opened, the flow of the reflux gas can be smoothly led straight without being narrowed or bent. Compared with the case where a valve is used, the pressure loss can be greatly reduced and the recirculation amount of the reflux gas can be easily increased, and the valve body is fitted and pressure-bonded to the valve seat so as to be highly airtight. It can be closed, and when the EGR valve is fully closed, the shut valve securely closes the upstream side of the EGR cooler, and the reflux gas enters and exits the EGR cooler through a slight gap and is continuously cooled. Therefore, it is possible to prevent deposits and deposits in the EGR cooler, and to avoid a decrease in efficiency and clogging of the EGR cooler.

  (II) According to the invention described in claim 2 of the present invention, since the angle range of the reciprocating arc motion of the arm is set to 90 ° or more, the valve body and the flow of the reflux gas when the shut valve is fully opened Since the interference can be avoided reliably, the pressure loss can be more reliably reduced.

  (III) According to the invention described in claim 3 of the present invention, since the pressing load of the valve body to the valve seat can be adjusted by the lever ratio, an appropriate pressing load is set to ensure high airtightness. It is possible to reliably close the upstream side of the EGR cooler with the shut valve when the EGR valve is fully closed, and to more reliably prevent deposits and deposits in the EGR cooler.

It is the schematic which shows an example of the form which implements this invention. It is the schematic which shows typically the drive mechanism of the shut valve of FIG. It is the schematic which shows a prior art example. It is sectional drawing which shows the example of a poppet type shut valve.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIGS. 1 and 2 show an example of an embodiment for carrying out the present invention. In this embodiment, it is extracted from the exhaust manifold 2 (exhaust system passage) in substantially the same manner as the conventional example of FIGS. 3 and 4 described above. The recirculated gas 4 ′ to the intake pipe 6 (intake system path), an EGR cooler 7 provided in the middle of the EGR line 5 for cooling the recirculated gas 4 ′, and an outlet of the EGR cooler 7 A flow of the recirculation gas 4 ′ is provided between the EGR valve 8 that is installed on the side and controls the recirculation amount of the recirculation gas 4 ′, and the recirculation gas 4 ′ outlet 2 a in the exhaust manifold 2 to the EGR cooler 7. The EGR device includes a shut-off valve 13 that shuts off. The shut-off valve 13 is configured as follows.

  That is, the shut valve 13 includes the valve seat 14 formed so as to surround the flow path of the reflux gas 4 ′ inside the EGR line 5 upstream of the EGR cooler 7, and the valve seat 14 as a fulcrum. An arm 15 that reciprocally moves between a proximity position and a separation position with respect to the seat 14, and is fitted to the valve seat 14 at a position close to the valve seat 14 and is refluxed by being fitted to the valve seat 14. The valve body 16 is configured as a swing type valve by closing the flow path of the gas 4 ′, and the valve body 16 is moved to a position where it does not interfere with the flow of the reflux gas 4 ′ flowing out from the flow path surrounded by the valve seat 14. The angle range θ of the reciprocating arc motion of the arm 15 is set to 90 ° or more so that it can be retracted.

  Here, as shown in FIG. 2, the drive mechanism of the arm 15 in the shut valve 13 is such that the reciprocating arc motion of the arm 15 is converted to the reciprocating linear motion of the air cylinder 18 (actuator) via the lever 17. More specifically, a rotary shaft 19 extending at a right angle from the base end portion of the arm 15 is rotatably arranged so that a fulcrum is set beside the valve seat 14, and the rotary shaft A lever 17 projecting from one end of 19 is pivotally attached to the tip of the air cylinder 18.

  FIG. 2 schematically shows the drive mechanism of the arm 15. For convenience of explanation, the lever 17 is projected to the opposite side to the projecting side of the arm 15, but the actual arm 15 and the lever are illustrated. 17 is arranged in a different phase in the longitudinal direction of the rotating shaft 19, and should be designed to have a compact layout by projecting both in the same direction.

  Thus, by doing so, the shut valve 13 is of a swing type, so that the valve body 16 can be largely separated from the valve seat 14 and the flow path of the reflux gas 4 ′ can be opened to the maximum. This is possible, and it is possible to guide the flow of the recirculation gas 4 ′ smoothly and straightly without being narrowed or bent. Compared with the case where the poppet type shut valve 9 (see FIG. 4) is adopted. Thus, the pressure loss can be greatly reduced and the recirculation amount of the reflux gas 4 'can be easily increased.

  In addition, since the valve body 16 is fitted and pressed against the valve seat 14 formed in the EGR line 5 upstream from the EGR cooler 7 so as to achieve a highly airtight blockage, the EGR valve 8 If the upstream side of the EGR cooler 7 is also tightly closed by the shut valve 13 when fully closed, the reflux gas 4 ′ is prevented from entering and exiting the EGR cooler 7 through a slight gap.

  As a result, the movement of the recirculation gas 4 ′ in the EGR cooler 7 due to the intermittent action of the exhaust pulsation is not repeated, and the recirculation gas 4 ′ is continuously cooled in the EGR cooler 7. Such a situation is avoided, and deposit adhesion in the EGR cooler 7 is prevented.

  Therefore, according to the above embodiment, when the shut valve 13 is fully opened, the flow of the reflux gas 4 ′ can be smoothly guided straight without being narrowed or bent, so that the poppet type shut valve 9 (FIG. 4). The pressure loss can be greatly reduced and the recirculation amount of the recirculation gas 4 ′ can be easily increased as compared with the case of using the reference), and the valve body 16 is fitted and crimped to the valve seat 14. It is possible to achieve a highly airtight blockage, the shut valve 13 firmly closes the upstream side of the EGR cooler 7 when the EGR valve 8 is fully closed, and the reflux gas 4 'enters and leaves the EGR cooler 7 through a slight gap. Therefore, it is possible to prevent the EGR cooler 7 from being deposited and deposited, and to prevent the EGR cooler 7 from being reduced in efficiency and clogging. It is possible to avoid a deer.

  In particular, in the present embodiment, the angle range θ of the reciprocating arc motion of the arm 15 is set to 90 ° or more, so that interference between the valve body 16 and the flow of the reflux gas 4 ′ when the shut valve 13 is fully opened is achieved. Since it can be avoided reliably, the pressure loss can be more reliably reduced.

  In addition, since the reciprocating arc movement of the arm 15 is performed by converting the reciprocating linear movement of the air cylinder 18 via the lever 17, the pressing load of the valve body 16 on the valve seat 14 is adjusted by the lever ratio. Therefore, it is possible to ensure a high airtightness by setting an appropriate pressing load.

  For this reason, an appropriate pressing load can be set to ensure high airtightness, and when the EGR valve 8 is fully closed, the shut valve 13 reliably closes the upstream side of the EGR cooler 7 and deposits in the EGR cooler 7. Can be more reliably prevented.

  Incidentally, in the case of the poppet type shut valve 9 (see FIG. 4) described above, the pressing load is almost determined by the diameter of the air cylinder 12 (see FIG. 4), so that the pressing load is determined at almost one point. Therefore, it is difficult to set an appropriate pressing load.

  The EGR device of the present invention is not limited to the above-described embodiment. In the drawing, the recirculation gas is returned to the intake pipe, but the intake system path for returning the recirculation gas is the intake manifold. Of course, the actuator is not limited to an air cylinder, and various modifications can be made without departing from the scope of the present invention.

2 Exhaust manifold (exhaust system)
2a Outlet 4 Reflux gas 5 EGR line 6 Intake pipe (intake system path)
7 EGR cooler 8 EGR valve 13 Shut valve 14 Valve seat 15 Arm 16 Valve element 17 Lever 18 Air cylinder (actuator)

Claims (3)

  An EGR line that guides the recirculated gas extracted from the exhaust system path to the intake system path, an EGR cooler that is provided in the middle of the EGR line to cool the recirculated gas, and is installed on the outlet side of the EGR cooler to An EGR device comprising: an EGR valve that controls a recirculation amount; and a shut valve that blocks a flow of the recirculation gas from a recirculation gas take-out port to the EGR cooler in the exhaust system, A valve seat formed so as to surround the flow path of the recirculation gas in the upstream EGR line, and an arm that performs a reciprocating arc motion between a proximity position and a separation position with respect to the valve seat around the valve seat as a fulcrum And the valve body, which is mounted at the tip of the arm and is fitted to the valve seat at a position close to the valve seat to close the flow path of the reflux gas. EGR apparatus characterized by being configured to queuing expression.   The angle range of the reciprocating arc motion of the arm is set to 90 ° or more so that the valve body can be retracted to a position where it does not interfere with the flow of the reflux gas flowing out from the flow passage surrounded by the valve seat. The EGR device described.   The EGR device according to claim 1 or 2, wherein the reciprocating arc motion of the arm is performed by converting the reciprocating linear motion of the actuator via a lever.

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